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热带玛珥湖湖水动力条件的变化,是反映区域有效降雨量的重要指标,为探测有效降雨的时空分布特征及其机制提供了良好的基础素材。对位于雷琼半岛的双池岭和湖光岩两个玛珥湖进行沉积物磁组构的分析,结果表明尽管湖泊沉积物磁面理发育、磁线理值很小,玛珥湖的水动力条件比较微弱,但各向异性度P和水流速度函数Fs呈现向上递减的长期趋势,与湖泊草本植物孢粉含量向上增加、有机碳含量减低、沉积物颜色从黑褐色向青灰色过渡的特征一致,反映了大约9cal.kaB.P.以来,华南区域有效降雨最逐渐增加、湖水平面上升的过程。这种变化的机理可能是当夏季风减弱时,热带辐合带(ITCZ)南移、ENSO活动加强的结果。
The change of hydrodynamic conditions in the tropical Maar Lake is an important index reflecting the effective rainfall in the area, providing a good basic material for detecting the spatiotemporal distribution and mechanism of effective rainfall. The magnetic field of sediments in Shuangchi Ridge and Huguangyan, located in the Lejin Peninsula, was analyzed. The results show that despite the development of the magnetic sediments in the lake sediments, the magnetic lineage values are very small. The water of Maar Lake However, the anisotropy P and water flow rate Fs showed a long-term trend of descending upwards. Compared with the increase of the spore-pollen content in lakes and herbs, the content of organic carbon decreased and the sediment color changed from dark brown to greenish-gray In line with this, reflecting the most effective increase in rainfall in southern China since about 9cal.kaB.P., the lake level rises. The mechanism of this change may be the result of intensification of ENSO activities when the summer monsoon weakens, the southward shift of the ITCZ.